hi to pajero masters!

when do you think it is advisable to replace the timing belt? should you go by the mileage or the number of years in service?

we have the same gen2 paj ng friend ko and he found out na malapit nang maputol yung belt although 70k pa lang mileage kaya lang mag-9 years na. he also found out na matagal nang putol yung isang belt sa ibaba ng timing belt mismo. i don't know kung para saan yun. he plans to replace the two in the soonest possible time but in the meantime he's risking his ride by driving with the broken smaller belt.

we almost have the same model although medyo "bata" ang ride ko by months so i'm anxious na baka malapit na ring maputol belt ko.

what purpose does the smaller belt have? sa tingin ko ok pa naman takbo ng paj ng friend ko kahit putol na ito.